Argentine  Ant:  Distribution 
tf  Control  in  the  United 


ar. 


States 


Ernest  R.  Barber 


UNIVERSITY  OF  CALIFORNIA 
AT    LOS  ANGELES 


UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 

BULLETIN  No.  377 


Washington,  D.  C. 


Contribution  from  the  Bureau  of  Entomology 
L.  O.  HOWARD,  Chief 


PROFESSIONAL  PAPER 


August  18,  1916 


'HE  ARGENTINE  ANT:     DISTRIBUTION  AND  CON- 
TROL  IN  THE  UNITED  STATES. 


EKNEST  R.  BAKBER,  Scientific  Assistant,  Southern  Field  Crop  Insect  Investi- 
gations. 


ent    known    distribution    in    the 

Southern  States 

Mspersion 

Dnomic  importance 


CONTENTS. 

Page. 


Page. 


Habits 

Life  history 

Natural  control 

Repression 


INTRODUCTION. 

The  Argentine  ant 2  is  one  of  the  most  serious  of  household  pests, 
uny  exposed  food  or  food  refuse  in  the  infested  sections  attracts  the 
workers  of  this  species  in  abundance,  and  residents  and  keepers  of 
jry  stores,  meat  markets,  confectioneries,  etc.,  must  either  suffer 
msiderably  or  almost  constantly  use  poison  or  barriers  of  various 
inds.    If  its  activities  were  confined  to  the  household  only,  the  prob- 
jm  of  controlling  the  Argentine  ant  would  be  sufficiently  difficult, 
in  common  with  some  other  ants  it  has  the  habit  of  protecting 
lealybugs  and  aphids  and  thus  indirectly  becomes  a  pest  of  crops. 
The  problem  is  more  serious  from  the  fact  that  the  species  is 
iadily  spreading  in  all  directions  throughout  the  Southern  States, 
is  practically  certain  that  it  was  introduced  into  this  country  at 
few  Orleans,  in  ships  which  brought  coffee  from  ports  in  Brazil, 
ilthough  the  exact  date  of  this  introduction  will  always  remain 
doubt. 

The  Argentine  ant  was  first  observed  in  New  Orleans  in  1891  by 
Edward  Foster.3     At  that  time  he  records  it  in  small  numbers 

1  The  work  of  the  Bureau  of  Entomology  on  the  Argentine  ant  is  divided  into  two  parts. 
ie  part  deals  with  the  ant  as  a  general  pest,  its  distribution,  and  relation  to  the  cultiva- 

fion  of  sugar  cane.  The  other  part  relates  to  the  special  problem  of  control  in  citrus 
jves.  This  phase  will  be  treated  in  another  publication.  The  work  reported  in  this 
iper  does  not  include  reference  to  conditions  in  California,  parts  of  which  State  are  also 
fested  by  the  Argentine  ant. 

2  Iridomyrmex  humilis  Mayr. 

8  Foster,  E.     The  introduction  of  Iridomyrmex  humilis  (Mayr)  into  New  Orleans.     Jour, 
eon.  Ent.,  v.  1,  no.  5,  p.  289-293.     1908. 
41860°— Bull.  377—16 1 


BULLETIN   377,   U.    S.    DEPARTMENT  OF   AGRICULTURE. 

nine  blocks  east  of  the  wharves  at  which  the  coffee  ships  usually  dis- 
charged their  cargoes.  It  may  be  surmised,  from  the  knowledge  we 
have  since  gained  from  studying  the  natural  dispersion  of  this  insect, 
that  it  has  been  in  the  country  for  about  45  years.  During  that  period 
it  has,  expanded  from  the  original  colony  to  myriads  of  colonies, 
extending  its  area  of  distribution  into  nine  Southern  States,  the 
many  infestations  covering  a  total  area  of  considerably  more  than  a 
thousand  square  miles. 

PRESENT  KNOWN  DISTRIBUTION  IN  THE  SOUTHERN  STATES. 
Newell  and  Barber,1  writing  in  1913,  recorded  the  known  distri- 
bution in  the  Southern  States  as  confined  to  Louisiana,  Mississippi, 


FIG.  1. — Map  showing  the  distribution  of  the  Argentine  ant  in  1913  (inner  line  of  small 
dashes)  and  at  the  end  of  1915  (outer  line  of  longer  dashes).  (Original.)  The  outer 
line  has  been  drawn  merely  to  connect  the  outlying  points.  It  incloses  some  territory  in 
which  the  ant  is  not  known  to  occur,  as,  for  instance,  western  Florida. 

and  Alabama,  and  established,  the  limits  of  this  dispersion  from 
Montgomery,  Ala.,  on  the  east,  to  Lake  Charles,  La.,  on  the  west,  a 
distance  of  380  miles,  and  from  Delta,  La.,  on  the  north,  to  the 
mouth  of  the  Mississippi  River,  a  distance  of  250  miles.  At  the 
present  time  the  limits  of  the  distribution  are  from  Houston,  Tex., 
on  the  west,  to  Wilmington,  N.  C.,  on  the  east,  and  from  Nashville, 
Tenn.,  to  the  mouth  of  the  Mississippi  River,  a  distance  of  1,100  miles 
east  and  west  and  500  miles  north  and  south  (map,  fig.  1).  Among 
the  cities  known  to  be  infested  are  Houston,  Tex.,  Shreveport.  La., 


1  Newell,  Wilmon,  and  Barber,  T.  C. 
Bui.  122,  p.  14.     1913. 


The  Argentine  Ant.     U.  S.  Dopt.  Agr.   Bur.  Ent. 


THE   ARGENTINE   ANT  :   DISTRIBUTION   AND  CONTROL. 

Texarkana,  Ark..  Nashville,  Term.,  Memphis,  Term.,  Augusta,  Ga., 
Atlanta,  Ga.,  Charleston,  S.  C.,  and  Wilmington,  N.  C. 

DISPERSION. 

Under  natural  conditions  the  Argentine  ant  spreads  very  slowly,  and 
this  spread  is  controlled  to  a  large  degree  by  the  available  food  supply.: 
Like  most  other  species  of  ants,  the  Argentine  ant  is  a  very  indusM 
trious  forager,  and  a  shortage  of  food  tends  to  hasten  its  dispersion.  ^ 
In  October,  1914,  a  small  infestation  covering  the  most  of  two  city 
blocks  was  found  in  Memphis,  Tenn.     The  ant  numbers  could  not 
have  increased  to  any  appreciable  extent  during  the  rather  long 
and  cold  winter  of  1914-15,  and  yet  in  the  early  part  of  the  following 
June  the  infestation  was  found  to  involve  nearly  the  whole  of  five 
blocks.    In  October,  1915,  it  developed  that  the  boundaries  had  not 
been  extended,  though  the  ant  numbers  had  greatly  increased.    The 
food  supply  must  have  increased  as  fast  as  did  the  numbers  of  ants. 

In  several  instances  frequent  observations  made  at  points  on  the 
frontier  of  the  infestation  developed  the  fact  that  the  normal  ad- 
vance will  average  from  300  to  400  feet  a  year.  The  abundance  of 
native  ants  has  some  influence  on  this  advance,  since  the  Argentine 
ant  will  not  tolerate  any  of  the  native  species,  and  in  consequence  a 
continuous  fight  is  waged  all  along  the  frontier. 

Heavy,  flooding  rains  are  undoubtedly  a  factor  in  the  natural  dis- 
tribution of  this  ant,  and  in  the  vast  region  drained  by  the  Mississippi 
"Elver  and  its  tributaries  it  will  be  remembered  that  there  are  at  least 
two  dangerous  flood  seasons  and  sometimes  more,  which  contribute  to 
and  accelerate  the  distribution  of  this  species.  Lumber,  rotting  trees, 
uprooted  shrubs,  cane  growth,  fruit,  vegetables,  and  all  manner  of 
refuse  contribute  to  the  mass  of  matter  borne  on  the  crest  of  flood 
water,  and  in  this  the  ants  seek  refuge  and  are  involuntarily  trans- 
ported.  Nature  has  endowed  this  species  with  a  remarkable  habit  of~~| 
self-preservation  from  drowning  in  times  of  floods,  for  when  rising  | 
water  floods  their  nests  and  no  other  means  of  escape  are  presented 
they  cluster  together  and  form  a  compact  ball.  The  immature  stagesj 
form  the  center  of  this  ball,  with  the  queens  and  workers  as  the  outer 
portion.  As  the  ball  enlarges  from  the  addition  of  other  workers 
which  had  been  struggling  alone  in  the  water  it  gradually  revolves. 
It  is  kept  revolving  slowly  by  the  outside  workers  continually  striv- 
ing to  reach  the  top  of  the  ball,  thus  permitting  air  to  reach  the 
interior.  The  writer  has  had  only  one  opportunity  of  witnessing  the 
formation  of  a  ball  of  this  kind.  After  a  5-inch  rainfall  several 
balls,  none  more  than  2  inches  in  diameter,  were  observed.  According 
to  reliable  authorities,  such  balls  have  been  observed  on  many  oc- 
casions, some  of  them  from  6  to  8  inches  in  diameter.  The  ants  in 


242745 


4  BULLETIN   377,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 

these  balls  disperse  when  they  come  into  contact  with  a  secure  resting 
place,  such  as  a  floating  piece  of  timber  or  land,  but  they  have  been 
seen  to  float  around  for  hours  on  still  water.  Mr.  Smith,  at  Daisy, 
La.,  states  that  he  destroyed  a  large  number  of  these  balls  by  pouring 
some  coal  oil  on  the  water.  The  balls  quickly  broke  up  when  in  con- 
tact with  the  oil  and  the  ants  died  in  a  very  short  time. 

Driftwood  is  another  important  carrier  of  this  pest.  A  fallen 
decayed  log  is  an  ideal  nesting  place.  Such  a  log  will  usually  decay 
from  the  underside  upward,  the  upperside  or  top  making  a  roof  for 
the  nest,  with  the  rotted  wood  below  drawing  and  retaining  ample 
moisture,  thus  affording  excellent  material  in  which  to  make  galleries. 
Logs  of  this  kind  are  light  and  easily  floated  and  are  important 
factors  in  spreading  infestations.  Especially  is  this  the  case  in  those 
parts'  of  the  country  where  heavy,  flooding  rains  occur.  In  this 
manner  practically  all  the  land  along  the  Mississippi  Eiver  below 
New  Orleans  has  been  infested. 

However,  it  is  to  the  vehicles  of  man  that  the  greatest  distribution 
must  be  credited.  The  most  important  are  steamboats  and  rail- 
roads. Commodities  are  carried  from  infested  territory  to  uninfested 
places  and  ant  colonies  are  often  to  be  found  in  shipping  boxes,  feed- 
ing on  sugar  and  other  grocery  supplies.  Practically  every  one  of 
nearly  a  hundred  steamboats  landing  between  New  Orleans  and 
Baton  Rouge  is  infested  with  the  Argentine  ant.  Further,  it  seems 
likely  that- this  ant  was  carried  by  boat  from  Charleston,  S.  C.,  to 
Wilmington,  N.  C.,  as  the  ant  is  to  be  found  around  the  wharves  and 
shipping  in  both  places.  So  gross  is  the  infestation  in  both  these 
cities  that  it  is  possible  that  the  species  may  have  been  introduced 
into  Charleston  many  years  ago  on  coffee  ships,  as  it  is  supposed  to 
have  been  introduced  into  New  Orleans,  the  slightly  colder  winters 
holding  it  more  in  check. 

When  inspecting  cities  far  removed  from  New  Orleans  it  has  been 
found  that  in  the  great  majority  of  instances  the  infestations  start 
immediately  around  the  wholesale-grocery  and  commission-merchant 
establishments.  This  indicates  that  when  carried  long  distances  the 
ants  are  more  likely  to  be  taken  through  in  solid  carload  lots  of  mer- 
chandise which  are  rushed  to  their  destination  than  in  smaller  con- 
signments. This  is  especially  the  case  with  perishable  goods  such 
as  fruit  and  vegetables.  Cars  containing  broken  shipments  are  side- 
tracked at  the  first  town  to  which  goods  are  consigned,  and  the  ants 
present  are  likely  to  leave  the  car  at  the  first  or  second  stop,  which 
fact  is  verified  in  that  nearly  all  the  small  towns  for  a  distance  of 
150  miles  from  New  Orleans  are  infested.  A  serious  feature  of  the 
infestation  of  inland  cities  such  as  Texarkana,  Memphis,  Atlanta, 
and  others,  is  that  the  ants,  having  become  established  in  the  whole- 
sale district,  are  readily  distributed  to  surrounding  smaller  towns 


THE  ARGENTINE   ANT:   DISTRIBUTION   AND  CONTROL.  5 

which  are  tributary  te  these  centers.  A  point  where  such  a  distribu- 
tion has  occurred  is  Summerville,  a  little  town  24  miles  north  of 
Charleston,  S.  C.,  which  has  become  infested,  presumably,  from  the 
latter  place. 

In  a  complete  colony  in  the  spring  of  the  year  three  distinct  forms 
of  adults  are  to  be  found — queens,  males  (drones),  and  workers,  the 
workers  greatly  outnumbering  both  the  queens  and  the  males.  The__ 
workers,  foragers  of  the  colony,  are  imperfect  females  with  no  re- 
productive functions.  The  queens,  which  are  the  reproducing  fe- 
males, remain  within  the  nest  nearly  all  the  time,  and  are  fed  and 
tended  by  the  workers.  The  males  have  apparently  but  one  func- 
tion— that  of  fertilizing  the  queens.  It  will  be  readily  understood 
that,  as  in  the  social  economy  of  ant  communities  of  other  species, 
it  is  absolutely  necessary  that  a  fertilized  queen  be  taken  along  with 
a  number  of  workers  before  a  new  colony  can  be  started.  It  is  quite 
possible  that  almost  every  town  and  city  in  the  Southern  States  has 
had  a  number  of  workers  introduced  at  one  time  or  another,  but 
owing  to  the  absence  of  a  queen  a  noticeable  infestation  has  not 
become  established.  Workers  alone  carried  in  this  manner  would  die 
out.  Such  may  be  the  case  at  Nashville,  Tenn.,  where  only  a  few 
workers  have  been  found.  Later  observations  will  be  necessary  to 
decide  this  question. 

ECONOMIC  IMPORTANCE. 

As  a  pest  in  cities  the  Argentine  .ant  has  no  equal.  Owing  to  its 
small  size  and  unobtrusive  color,  it  is  able  to  invade  practically  every 
part  of  ordinary  dwellings,  stores,  etc.  It  is  almost  omnivorous, 
eating  most  cooked  foods  and  a  considerable  percentage  of  the  raw 
foods  that  are  to  be  found  in  the  average  pantry.  It  exhibits  a 
marked  preference  for  some  foods,  such  as  sugar,  sirup,  honey,  jams, 
cakes,  candies,  pies,  fruit,  and  meats  of  all  kinds.  The  temperature 
of  refrigerators  or  ice  boxes  seems  to  have  no  deterrent  effect,  and 
ants  will  readily  invade  them. 

It  is  a  common  occurrence  for  Argentine  ants  to  invade  bed- 
chambers, and  while  they  do  not  possess  a  sting,  they  can  cause 
considerable  pain  with  their  mandibles.  There  have  been  many 
reports  of  babies  being  attacked  by  them  in  such  numbers  as  to 
cause  serious  results,  and  several  of  these  reports  have  been  verified. 
In  August,  1915,  the  writer  located  such  a  case  in  Augusta,  Ga. 
A  reputable  citizen  of  that  city,  residing  in  a  heavy  infestation  of 
the  Argentine  ants,  gave  the  following  account  of  such  an  attack  on 
his  4-weeks-old  baby : 

We  were  awakened  in  the  night  by  a  weak  cry  from  the  baby,  and  when 
the  light  was  turned  on  the  baby's  face  was  black  with  ants.  They  were  in  the 
baby's  nose,  ears,  and  mouth.  We  hurriedly  carried  the  baby  to  the  bathtub 


6  BULLETIN   377,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 

and  started  to  wash  off  the  ants.  It  took  us  nearly  an  hour  and  a  half  to  get 
the  last  ant  off  the  baby.  I  feel  sure  that  if  we  had  not  heard  the  cry,  in  a  few 
hours  the  child  would  have  perished. 

With  conditions  made  almost  intolerable  in  badly  infested  places, 
it  is  not  uncommon  to  find  empty,  unrentable  houses.  Realty  values 
accordingly  drop. 

The  nurseryman  ana  truck  grower  are  greatly  molested  by  this 
pest,  owing  to  the  ant's  fondness  for  the  honeydew  of  aphids  and 
scale  insects.  The  ants  take  the  best  possible  care  of  these  honey- 
yielding  species,  and  protect  them  from  their  natural  enemies,  fre- 
quently building  mud  shelters  over  them,  and  as  the  host  plants 
grow,  carry  the  young  scales  and  aphids  and  place  them  on  the 
young  tender  growth,  where  they  may  more  easily  sap  the  juices 
of  the  plants. 

Newell  and  Barber1  give  a  very  graphic  account  of  the  manner 
in  which  the  Argentine  ant  has  invaded  the  orange  orchards  of 
Louisiana. 

In  corn,  cotton,  and  sugar-cane  fields  the  Argentine  ant  when 
present  is  constantly  attending  the  aphids  and  mealy  bugs,  increasing 
the  numbers  of  these  species  to  an  alarming  degree,  much  to  the 
detriment  of  the  plants.  The  writer  has  determined  that  a  consider- 
able loss  of  sugar  results  from  the  attendance  of  the  Argentine  ant 
on  the  sugar-cane  mealy  bug. 

HABITS. 

Argentine  ants  are  extremely  social  among  their  own  kind,  the 
individuals  never  having  been  observed  to  quarrel  with  one  another, 
nor  one  colony  with  another.  Workers  may  be  carried  for  miles  and 
placed  with  others  of  their  kind  and  no  apparent  demonstrations 
of  like  or  dislike  are  exhibited.  The  newcomers  appear  to  enter 
into  the  colony  spirit  and  are  soon  lost  to  the  view  of  an  observer. 
Any  small  nest  will  contain  several  queens  which  live  together 
amicably. 

The  summer  nest  may  be  located  anywhere — under  sidewalks, 
under  the  sills  of  houses,  in  brick  piles,  stone  piles,  under  a  piece  of 
board  or  a  piece  of  tin,  in  an  old  tin  can — in  fact,  in  any  place  con- 
venient to  the  food  supply.  In  the  winter  months  there  is  a  tendency 
to  concentrate  into  larger  colonies,  and  they  seek  warn*,  dry,  secure 
nesting  places  in  which  to  hibernate.  These  desirable  places  are  not 
plentiful,  and  where  one  is  located  the  ants  from  some  distance  will 
seek  its  shelter.  The  winter  is  the  most  hazardous  period  of  the  year, 
for  should  a  nest  by  any  chance  be  flooded  during  a  cold  spell,  when 
the  ants  are  dormant,  the  chances  of  survival  of  the  colony  would  be 
extremely  slight.  Usually  throughout  the  latter  part  of  December, 

1  Op.  cit,  p.  24. 


THE  ARGENTINE  ANT  :   DISTRIBUTION   AND  CONTROL.  7 

January,  and  February  (at  New  Orleans)  these  large  colonies  are 
found.  They  sometimes  reach  very  extensive  proportions  and  may 
contain  several  hundred  queens  and  countless  workers  and  immature 
stages.  These  colonies  are  usually  located  at  the  base  of  large  trees 
on  high,  well-drained  spots  of  ground,  in  manure  piles,  or  in  any  other 
piles  of  decomposing  rubbish  where  heat  is  generated.  A  warm  day 
will  make  them  particularly  active,  and  they  will  form  trails  in  all 
directions  from  these  winter  nests  to  food  supplies.  They  may  be 
observed  traversing  the  trunks  of  trees  every  warm  winter  day,  and 
from  the  trees  trails  are  made  to  nearby  houses,  where  they  cause 
considerable  annoyance. 

With  the  advent  of  warm  spring  weather  the  breaking  up  of  the 
large  colonies  occurs.  This  is  the  time  of  the  year  that  food  is  very 
scarce,  and  at  this  season  the  ants  are  particularly  aggressive  and 
troublesome  in  the  houses.  This  is  the  best  time  to  use  poisoned  sirup, 
which  will  be  described  later,  for  controlling  this  pest. 

LIFE  HISTORY. 

There  are  three  adult  forms  to  be  found  within  a  complete  nest  in 
the  spring  months  of  the  year — the  queen,  the  male,  and  the  worker. 
A  colony  may  be  complete,  however,  with  a  queen  and  workers. 
Three  immature  forms  are  also  present — the  egg,  larva,  and  pupa. 

EGG. 

In  an  artificial  formicary  a  fertilized  queen  lays  from  3  to  30  eggs 
per  day  when  ample  food  is  supplied.  It  is  very  probable  that  under 
natural  conditions  the  egg  production  is  considerably  more.  Only  a 
few  seconds  are  occupied  for  the  laying  of  each  egg.  A  worker, 
apparently  awaiting  the  arrival  of  the  egg,  picks  it  up  and  transfers 
it  to  a  pile  of  eggs  already  in  the  nest.  The  surface  of  the  egg  is 
somewhat  mucilaginous  and  readily  sticks  to  other  eggs.  This  per- 
mits the  workers  to  handle  the  eggs  en  masse  and  also  permits  of 
their  being  deposited  in  desirable  locations  on  the  walls  and  ceilings 
of  the  galleries. 

The  egg  when  first  laid  is  about  0.3  mm.  long  and  0.2  mm.  wide. 
It  is  elliptical,  pearly  white,  lustrous,  and  without  markings.  As  the 
time  for  hatching  approaches  the  luster  disappears.  It  is  extremely 
difficult  to  detect  the  exact  time  of  hatching.  The  average  summer 
incubation  period  is  about  15  days,  but  this,  of  course,  is  subject  to 
the  variations  of  temperature  and  humidity  during  this  period. 

LARVA. 

The  larva,  when  first  hatched,  is  creamy  white.  Its  body  is  very 
curved,  but  it  gradually  straightens  as  the  larval  growth  continues. 
It  is  entirely  helpless  and  is  practically  motionless. 


8  BULLETIN"   377,   U.    S.    DEPARTMENT  OF   AGRICULTURE. 

The  workers  feed  and  cleanse  the  larvae,  moving  them  about  with 
the  fluctuations  of  temperature  and  humidity  to  the  most  desirable 
places  within  the  nest.  The  full-grown  worker  larva  is  about  1.5 
mm.  long  by  0.65  mm.  wide.  The  average  larval  period  throughout 
the  summer  months  under  normal  conditions  is  about  13  days. 

PUPA. 

When  the  pupal  stage  is  reached  the  sex  of  the  individual  is 
readily  distinguishable.  The  pupa  is  white,  with  the  exception  of 
two  distinct  black  eyespots  on  the  sides  of  the  head.  The  worker 
pupa  is  about  2  mm.  long,  the  head  and  thorax  being  the  larger  part 
of  it.  The  male  pupa  is  about  50  per  cent  larger  than  the  worker 
pupa,  and  the  queen  is  still  larger,  The  two  latter  forms  may  be 
readily  distinguished  from  the  worker  pupa.  The  male  pupa  has 
a  very  large  thorax  and  a  small,  closely  coupled  abdomen,  while  the 
queen  pupa  is  much  more  symmetrical,  the  thorax  is  not  so  large, 
and  the  abdomen  much  larger  than  that  of  the  male.  The  pedicel 
between  the  thorax  and  abdomen  of  the  queen  pupa  is  more  con- 
stricted and  elongated  than  in  the  male  pupa. 

After  the  first  few  days  the  color  of  the  pupa  gradually  changes 
to  creamy  yellow  and  continues  to  darken  until  a  light-brown  color  is 
reached  just  previous  to  emergence. 

The  duration  of  the  pupal  stage  of  the  worker  throughout  the 
summer  months  averages  about  13  days,  while  that  of  the  male  is 
about  22  days.  No  records  have  been  established  of  the  duration  of 
the  pupal  period  of  the  queen. 

The  pupae  of  all  the  stages  are  aided  in  transformation  by  the  work- 
ers. Upon  first  emerging  the  adult  is  of  a  light-brown  color  which 
gradually  grows  darker  until  the  second  day,  when  it  becomes  indis- 
tinguishable from  other  adults. 

DEVELOPMENTAL  PERIOD. 

By  compounding  the  average  periods  of  development  of  the  egg, 
larva,  and  pupa,  a  general  average  of  40  days  results,  which  repre- ' 
sents  the  complete  development  from  egg  to  adult  in  the  case  of 
the  worker  and  a  somewhat  longer  period  for  the  males  and  queens. 

ADULT  FORMS. 

The  worker  is  about  2.5  mm.  in  length  and  of  a  dark-brown  color, 
and  there  is  only  one  caste.  The  workers  forage  for  food,  attend  the 
queen  and  the  young,  and  fight  to  protect  the  colony.  A  large  per- 
centage of  the  workers  stay  within  the  nest  at  all  times  and  are 
always  ready  for  any  emergency,  whether  it  be  to  fight  invaders  or 
to  hurriedly  seize  the  immature  stages  and  retreat  to  securer  locations 
upon  the  slightest  indications  of  rain  or  flood. 


THE   AEGEXTIXE   AXT  :    DISTRIBUTIOX    AXD   COXTEOL.  9 

The  workers  are  able  to  carry  considerable  liquid  food  in  their 
abdomens,  which  become  distended  and  transparent.  This  food  is 
regurgitated  when  the  nest  is  reached,  and  fed  to  the  immature  forms 
and  other  workers  and  queens  in  the  nest.  They  are  quite  long  lived 
and  have  been  kept  in  artificial  formicaries  for  many  months  at  a 
time.  It  is  quite  possible  that  they  may  live  a  year  under  natural 
conditions. 

The  male  is  always  winged.  It  is  readily  distinguished  by  its  mas- 
sive thorax,  small  head,  and  abdomen.  It  is  about  3  mm.  in  length, 
and  the  body  color  is  of  a  dark  brown,  the  same  shade  as  the  worker. 
Males  appear  in  the  nest  in  the  spring  months  of  the  year  and 
gradually  lessen  in  numbers  as-  the  summer  advances. 

When  the  queen  first  emerges  she  is  winged,  but  at  the  time  of 
copulation,  or  about  that  time,  she  loses  her  wings,  and  her  activities 
from  that  time  are  devoted  to  egg  producing.  The  dealated  queen 
is  about  6  mm.  long  and  of  the  same  color  as  males  and  workers.  It 
is  seldom  that  the  queens  leave  the  nest  unless  disturbed,  but  occa- 
sionally they  may  be  seen  crawling  along  an  ant  trail  in  company 
with  the  workers.  At  rare  intervals  they  travel  alone  and  may  be 
observed  wandering  about  aimlessly. 

The  queens  have  frequently  been  kept  within  artificial  formicaries 
for  more  than  a  year,  and  it  is  reasonable  to  suppose  that  they  will 
live  much  longer. 

NATURAL  CONTROL. 

It  would  appear  that  heavy  rains  and  resulting  flood  are  the  only 
factors  of  natural  control  of  any  great  importance.  They  are  espe- 
cially effective  if  occurring  during  cold  weather,  for  at  this  time  the 
ants  are  sluggish  and  unable  to  exert  themselves.  Moderately  cold 
weather  does  not  appear  to  check  their  activities. 

On  Xovember  18,  1911,  a  heavy  infestation  of  this  ant  was  discov- 
ered at  Kosciusko,  Miss.,  about  half  the  town  being  infested.  Resi- 
dents stated  that  they  had  been  troubled  for  about  7  years;  several 
of  them,  owing  to  the  great  annoyance,  had  moved  to  parts  of  the 
town  which  were  not  then  infested.  On  revisiting  Kosciusko  in 
April,  1912,  the  infestation  had  decreased  to  such  an  extent  that  it 
was  quite  difficult  to  find  any  of  the  ants.  The  meteorological 
records  of  the  winter  months  revealed  the  following  striking  facts: 
The  mean  average  temperature  of  the  6  months  from  Xovember  to 
April,  inclusive,  was  49.5°,  but  the  rainfall  for  this  period  was  exces- 
sive, reaching  the  total  of  41.1  inches,  whereas  the  average  10  years' 
precipitation  for  these  months  had  been  only  27  inches.  This  con- 
trol was,  however,  only  temporary.  In  June,  1915,  Kosciusko  was  ' 
again  visited  and  the  ants  were  found  to  be  very  numerous  and 
causing  great  annoyance  to  residents.  The  infestation  had  spread 
41860°— Bull.  377—16 2 


10  BULLETIN   377,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

over  practically  the  whole  town,  as  well  as  near-by  corn  and  cotton 
fields. 

During  the  same  winter  (1911-12)  similar  conditions  were  expe- 
rienced at  New  Orleans,  the  winter  months  being  accompanied  by  a 
rainfall  of  41.56  inches,  as  compared  to  the  10-year  average  of  but 
26.1  inches.  The  numbers  of  ants  were  greatly  reduced,  the  mortality 
probably  being  at  least  70  per  cent.  The  ability  of  this  species  to 
overcome  such  a  catastrophe  was  well  illustrated,  for  by  September, 
1912,  the  ants  had  apparently  reached  their  maximum  numbers. 

REPRESSION. 

OUTDOOR  BARRIERS. 

A  number  of  experiments  have  been  conducted  to  discover,  if 
possible,  an  efficient  outdoor  barrier. 

The  sticky  substance  which  is  used  in  coating  flypaper  and  is  also 
sold  in  bulk  for  banding  trees  was  effective  for  only  a  few  days.  The 
ants  would  carry  particles  of  dirt  and  build  a  bridge  over  it.  This 
substance,  made  much  thinner  than  usual,  as  suggested  by  Mr.  D.  M. 
Rogers  for  use  in  the  gipsy-moth  work,  was  tried  and  with  more 
successful  results.  Heavy  bands  4  inches  wide  spread  on  two  mag- 
nolia trees  were  effective  for  two  months  in  the  summer  without 
having  to  be  replenished  or  combed.1 

In  the  cooler  parts  of  the  year  these  bands  require  frequent  atten- 
tion on  account  of  the  growth  of  mold  on  the  surface.  During  wet 
weather  in  the  winter  in  Louisiana  this  mold  will  form  in  a  very 
few  days,  and  the  efficiency  of  the  sticky  band  will  be  entirely 
destroyed. 

It  was  found  that  5  per  cent  of  a  carbolized  oil  added  to  the  thinner 
preparation  increased  the  effectiveness  of  the  bands  considerably 
and  entirely  prevented  the  growth  of  mold.  The  bands  were  also 
rendered  more  repellent  and  more  resistant  to  winter  conditions.  A 
thin  crust  forms  over  the  surface  of  the  bands  in  the  winter,  but  this 
is  readily  combed  into  the  band  in  the  spring  and  the  band  is  as 
effective  as  ever.  The  crust  on  bands  of  the  thinner  preparation 
without  the  carbolized  oil  becomes  too  hard  during  the  winter,  and 
it  is  necessary  to  use  fresh  material  in  the  spring.  These  bands 
were  used  on  fig,  magnolia,  pecan,  and  orange  trees  and  no  injury  to 
the  trees  was  apparent.  There  is  a  possibility  that  the  substance 
may  be  harmful  to  trees  with  a  more  tender  bark,  however. 

To  the  thinner  preparation  were  added  in  different  tests  1  per 

cent  of  bichlorid  of  mercury,  2  per  cent  of  nicotine  sulphate.  10  per 
»_ 

1 A  wooden  comb  is  supplied  by  the  manufacturers  for  the  purpose  of  combing  the  bands 
when  a  coating  of  dirt,  insects,  or  any  other  foreign  matter  collects  on  the  band.  This 
foreign  material  is  mixed  in  with  a  clean  sticky  substance,  immediately  under  the  surface 
of  the  band,  and  the  band  is  as  efficient  as  ever. 


THE  ARGENTINE   ANT:   DISTRIBUTION   AND   CONTROL.  H 

cent  of  naphthalene,  and  several  other  repellents.  While  bands  con- 
taining bichlorid  of  mercury  and  nicotine  sulphate  were  effective 
for  slightly  longer  periods  than  the  sticky  substance  alone,  their  use 
is  hardly  to  be  recommended. 

INDOOR  BARRIERS. 

Perhaps  the  most  effective  and  durable  barrier  which  can  be  used 
indoors  is  a  bichlorid-of  -mercury  tape  or  band.  Tape  is  soaked  in  a 
saturated  solution  of  bichlorid  of  mercury  and  then  hung  up  to  dry. 
It  is  then  placed  around  the  legs  of  tables,  safes,  etc.,  and  if  it  is  kept 
dry  will  last  from  six  months  to  a  year.  Common  lampwick  one-half 
an  inch  wide  is  ideal  for  this  purpose.  After  it  has  been  treated  in  a 
saturated  solution  of  bichlorid  of  mercury  and  dried,  pieces  are 
wrapped  around  the  leg  of  the  piece  of  furniture  to  be  isolated  and 
ends  lapped  over  tightly  and  pinned.  The  tape  can  be  readily  re- 
newed by  another  soaking  in  bichlorid  of  mercury  and  repinned  in 
place. 

Twenty-five  per  cent  of  bichlorid  of  mercury  mixed  in  shellac  may 
be  painted  around  the  legs  of  furniture,  and  when  dry  it  will  be  quite 
as  satisfactory  as  the  tape. 

Extreme  caution  is  advised  in  handling  bichlorid  of  mercury,  as 
there  is  always  an  element  of  danger  in  using  this  poison.  In  recent 
years  the  sale  of  this  drug  to  the  layman  has  been  practically  dis- 
continued. 

A  simple  and  efficient,  though  perhaps  unsightly,  barrier  may  be 
made  by  placing  the  legs  of  furniture  in  saucers  and  putting  a  gen- 
erous supply  of  moth  balls  in  each  saucer.  The  moth  balls  will 
slowly  volatilize,  and  it  is  necessary  to  add  more  from  time  to  time, 
but  the  ants  will  not  cross  the  barrier  thus  formed. 

Coal  oil  placed  in  saucers  in  which  the  legs  of  furniture  rest  will 
repel  the  ant,  but  the  odor  of  the  oil  is  disagreeable  to  most  persons. 


Many  and  varied  experiments  have  proved  that  it  is  futile  to  try 
to  exterminate  Argentine  ants  with  a  poison  which  kills  rapidly.  A 
few  workers  may  be  killed,  but  the  masses  of  ants  will  quickly  recog- 
nize the  source  of  fatality  and  avoid  the  "  doctored  "  food.  The  few 
workers  killed  in  this  way  will  have  no  effect  in  reducing  the  numbers. 
Xone  of  this  poison  will  reach  the  queens  in  the  nest,  and  it'has  been 
found  that  it  is  essential  to  kill  off  the  queens  in  order  to  prevent 
further  multiplication  of  the  pest. 

Soon  after  the  writer  took  up  the  work  on  the  Argentine  ant  Mr. 
L.  J.  Nickels1  published  an  article  on  the  control  of  the  Argentine 
ant  in  California,  in  which  a  rather  successful  poisoned  sirup  was 
described.  It  was  decided  to  give  this  poisoned  sirup  a  thorough  trial 

1  Nickels,  L.  J.  Field  Work  in  the  Control  of  the  Argentine  Ant.  Jour.  Econ.  Ent., 
V.  4,  no.  4,  pp.  353-358.  1911. 


12  BULLETIN   377,   U.    S.    DEPARTMENT  OF   AGRICULTURE. 

in  the  Southern  States.     The  following  experiment  is  based  on  Mr. 
Nickels's  recommendations : 

EXPERIMENT  AT  HATTIESBTJRG,  MISS. 

At  Hattiesburg,  Miss.,  an  infestation  of  8  blocks  was  found  to  be 
an  ideal  place  for  this  experiment. 

The  following  buildings  were  located  within  the  infestation: 
Thirty-eight  residences,  7  stores,  2  meat  markets,  2  small  hotels,  2 
restaurants,  2  bottling  establishments  (which  will  be  designated  here- 
after as  establishment  A  and  establishment  B),  a  laundry,  a  marble 
factory,  a  sawmill  and  office,  and  a  church. 

Thirty  dozen  1-pint  fruit  jars  were  prepared  in  the  manner  out- 
lined by  Mr.  Nickels.  The  porcelain  was  broken  out  of  the  metal 
tops  and  five  holes  about  three-eighths  inch  in  diameter  were  punched 
near  the  center  of  each  top.  Sponges  were  cut  up  into  pieces  and  a 
piece  inserted  in  each  jar.  The  piece  of  sponge  filled  about  a  third  of 
the  space  in  the  jar. 

A  gill  of  the  poisoned  sirup  was  put  into  each  jar.  On  each  jar 
was  pasted  a  poison  label. 

On  September  28,  25  dozen  of  these  jars  were  distributed — about 
six  jars  placed  in  each  house  and  store.  Two  vacant  blocks  were 
not  covered  at  this  time,  but  on  November  16,  3  dozen  jars  were  dis- 
tributed on  these  blocks.  As  the  jars  had  to  be  placed  outdoors,  they 
were  laid  on  one  side  to  prevent  rain  from  entering.  The  residents 
of  the  other  blocks  were  questioned  as  to  results,  and  they  reported 
very  favorably.  In  most  cases  the  ants  had  become  much  less  abun- 
dant. The  two  meat  markets  had  fewer  ants  than  before,  but  the 
sirup  rooms  of  both  bottling  establishments  were  as  badly  infested  as 
ever,  the  ants  evidently  preferring  the  flavored  sirups  to  the  poisoned 
sirup. 

In  the  latter  part  of  April,  1912,  the  infestation  was  again  deter- 
mined. This  was  immediately  after  the  winter  previously  referred  to, 
when  the  infestation  had  been  so  reduced  at  Kosciusko  and  New 
Orleans.  Though  the  numbers  of  ants  had  certainly  been  reduced  in 
Hattiesburg,  they  were  still  present  in  proportionately  greater  num- 
bers than  in  New  Orleans.  It  is  likely  that  the  better  wintering 
facilities  at  Hattiesburg  were  due  particularly  to  excellent  drainage 
and  the  presence  of  numerous  trees. 

On  June  18  another  inspection  was  made.  The  numbers  of  ants 
were  at  this  time  about  60  per  cent  of  what  they  were  during  the 
previous  November.  The  eastern  line  of  infestation  had  not  been 
extended  and  the  ants  were  giving  little  trouble  in  the  houses,  though 
they  had  apparently  concentrated  around  the  sirup  rooms  of  both 
bottling  establishments.  The  stores  and  meat  markets  had  not  been 
troubled  to  any  extent,  but  there  were  many  trails  of  ants  on  the 
trees.  Many  of  the  jars  were  examined,  and  it  was  found  that  a  de- 


THE  ARGENTINE  ANT:   DISTRIBUTION   AND  CONTROL.  13 

composition  had  taken  place  in  the  sirup  in  the  jars,  a  very  disagree- 
able odor  being  given  off.  As  many  of  the  jars  as  could  be  found  were 
collected.  These  were  thoroughly  cleaned,  especially  the  sponges, 
which  were  washed  in  boiling  water.  Fresh  sirup  was  prepared  and 
the  jars  recharged  and  again  distributed. 

The  jars  were  again  recharged  in  October.  At  this  time,  though 
the  infestation  had  not  spread,  the  ants  were  more  numerous.  They 
were  very  numerous  in  the  sirup  rooms  of  both  bottling  establish- 
ments, and  in  both  meat  markets. 

Observations  were  made  in  December,  and  at  this  time  conditions 
were  fairly  satisfactory.  Ants  had  troubled  only  two  of  the  houses, 
in  each  instance  only  for  a  day  or  so,  and  had  theji  left.  The  bottling 
establishments  were  closed  for  the  winter.  The  intention  was  to 
recharge  the  jars  at  this  time,  but  the  status  was  so  satisfactory  that 
it  was  decided  to  leave  them  until  the  following  spring. 

In  the  beginning  of  April  the  ants  were  not  very  plentiful.  Only 
three  houses  had  been  invaded  during  the  winter.  The  sirup  rooms 
of  both  bottling  works  were  again  besieged. 

By  the  latter  part  of  May  the  ants  were  more  numerous  all  over 
the  infested  area,  though  none  of  the  residents  or  storekeepers  had 
so  far  been  troubled.  The  proprietor  of  bottling  establishment  A 
now  had  his  sirups  isolated  and  the  ants  were  noticeably  fewer 
around  this  building,  but  they  were  in  increased  numbers  around  the 
other  plant.  The  ants  were  now  very  numerous  on  one  block,  and  as 
the  jars  had  not  been  satisfactory  outdoors,  special  paraffin-covered 
rainproof  paper  bags  were  prepared  to  place  on  the  trees  near  the 
houses  and  along  the  streets  throughout  the  infested  area.  The 
experiment  had  been  conducted  for  20  months  and  the  results  had 
not  been  entirely  satisfactory.  The  ants  had  been  almost  completely 
kept  out  of  the  houses  and  stores,  except  the  sirup  rooms  of  the 
bottling  works,  but  large  numbers  were  still  present  outdoors. 

It  is  fairly  conclusive  that  the  sirup  within  the  houses  repelled  the 
ants,  for  even  in  the  spring  the  ants  gave  little  trouble  to  the  resi- 
dents. 

On  July  9,  50  paper  bags l  containing  this  sirup  were  placed  on 
trees  throughout  the  infested  area.  About  half  of  these  bags  were 
placed  on  trees  in  one  block.  All  the  bags  were  tacked  about  15  feet 
above  the  ground  to  keep  them  out  of  reach  of  children  and  to  arrest 
evaporation  as  much  as  possible,  bags  at  this  height  being  in  the 
shade. 

On  August  13  a  status  inspection  was  made,  and  very  remarkable 
results  were  observed.  There  were  not  at  this  time  more  than  20 
per  cent  of  the  ants  on  the  trees  as  compared  with  July,  and  all  of 
the  houses  without  exception  situated  anywhere  near  the  trees  had 

1A  description  of  the  preparation  of  this  bag  is  given  on  pages  20  and  21. 


14  BULLETIN   377,   U.   S.   DEPAETMENT  OF   AGRICULTURE. 

been  invaded.  None  of  the  stores  along  Bay  Street,  near  which  were 
no  trees,  had  been  bothered  by  the  ants.  All  the  jars  were  recharged. 

In  November  conditions  were  very  satisfactory.  Comparatively 
few  ants  were  to  be  seen,  and  these  were  mostly  on  the  trees.  No 
ants  wTere  to  be  found  in  the  sirup  room  of  bottling  establishment  A, 
and  there  were  A*ery  few  in  the  vicinity  of  the  building.  There  were 
very  few  ants  on  the  trees  in  one  block.  By  far  the  largest  number 
of  ants  were  to  be  found  around  the  building  in  which  bottling  estab- 
lishment B  had  been  located.  People  in  the  house  next  to  this  build- 
ing w?ere  being  considerably  troubled. 

In  January,  1914,  all  the  jars  were  recharged  and  150  paper  bags 
containing  the  poisoned  sirup  were  distributed  over  the  infested  area. 

On  April  7  a  thorough  inspection  was  made,  and  the  numbers  of 
ants  were  found  to  be  greatly  reduced.  Nowhere  had  the  ants  caused 
any  annoyance.  There  were  very  few  ants  on  any  of  the  trees.  In 
several  places  native  ants  had  again  taken  up  their  abode  within  the 
infested  area,  indicating  that  the  Argentine  species  wras  dying  out. 

In  the  latter  part  of  May  the  jars  were  recharged  and  300  poison 
bags  placed  in  suitable  locations.  An  inspection  at  that  date  proved 
that  the  experiment  was  continuing  very  satisfactorily. 

Native  ant  nests  could  be  found  dotted  over  the  whole  area.  The 
largest  number  of  Argentine  ants  was  found  around  the  abandoned 
building  of  bottling  establishment  B ;  in  fact,  this  was  the  only  place 
where  the  ant  could  be  found  in  large  numbers. 

An  inspection  on  June  29  indicated  that  the  experiment  was  pro- 
gressing favorably.  The  numbers  of  Argentine  ants  around  bot- 
tling establishment  B  had  greatly  decreased,  it  being  actually  diffi- 
cult to  find  them  on  these  premises.  Not  a  vestige  of  the  infestation 
could  be  found  on  three  of  the  blocks. 

In  mid-September  the  territory  was  again  inspected.  The  condi- 
tions were  found  to  be  excellent.  Scarcely  an  Argentine  ant  could 
be  seen  in  any  part  of  the  once-infested  territory. 

Everyone  living  in  the  formerly  infested  area  was  of  the  opinion 
that  the  Argentine  ants .  had  been  completely  eradicated,  but  the 
writer  found  a  few  workers.  However,  he  decided  to  consider  the 
experiment  concluded,  for  the  time  at  least.  It  was  possible  that 
the  queens  were  all  destroyed  and  that  just  a  few  workers  remained. 
Theje  was  also  the  possibility  of  the  native  ants  finally  exterminating 
the  Argentine  species. 

The  poisoned  sirup  had  finally  proved  efficient,  though  it  must  be 
stated  that  it  was  necessary  to  expose  it  both  indoors  and  out. 

IMPROVEMENT  OF  THE  NICKELS   SIRUP. 

In  the  tests  with  the  Nickels  sirup  a  number  of  objectionable 
features  were  encountered  which  finally  led  to  the  preparation  of  a 


THE  ARGENTINE   ANT:   DISTRIBUTION   AND  CONTROL.  15 

greatly  modified  sirup.  In  all  the  experiments  the  sirup  proved  very 
attractive  and  palatable  to  the  ants  at  first,  but  their  visits  gradually 
decreased  until  the  sirup  was  avoided,  although  in  some  instances  the 
trails  continued  to  pass  by  the  poison  jars.  The  period  of  attendance 
at  the  sirup  varied  somewhat  with  the  seasons,  being  longer  in  winter. 
Even  in  the  winter,  however,  a  repellent  action  was  apparent.  In 
preparing  the  solution  it  had  been  noticed  that  the  sirup  turned 
brown,  becoming  darker  the  longer  it  was  boiled,  although  it  was 
made  in  a  pail  which  in  turn  was  placed  in  a  bath  to  prevent  burning. 

Another  objection  was  the  crystallization  of  the  sirup  to  a  greater 
or  less  extent  upon  cooling.  On  the  advice  of  a  sugar  chemist  the 
proportion  of  water  was  increased  to  make  a  saturated  sugar  solu- 
tion ;  10  pounds  of  water  to  20  pounds  of  sugar  and  1  ounce  of  sodium 
arsenite  were  used.  The  Nickels  sirup,  contained  one-fourth  per  cent 
arsenic,  while  this  more  dilute  sirup  contained  one-fifth  per  cent, 
but  the  dilute  sirup  was  quite  effective.  With  the  exception  of  the 
first  application,  the  dilute  sirup  was  used  throughout  the  length 
of  the  Hattiesburg  experiment.  Crystallization  of  from  5  to  15 
per  cent  of  the  weight  of  sirup  still  occurred  in  short  periods,  but 
as  high  as  50  per  cent  when  the  sirup  had  been  in  the  jars  for  several 
months.  This  of  course  had  the  effect  of  proportionally  increasing 
the  percentage  of  poison  in  the  liquid  and  consequently  its  repellent 
power.  Newly  made  sirup  appeared  to  be  less  repellent  than  that 
which  had  stood  for  several  weeks. 

The  repellent  action  of  the  sirup  is  illustrated  by  an  experiment 
conducted  in  a  private  residence,  which  was  badly  overrun  with  ants. 
The  ants  were  abundant  in  the  refrigerator,  safe,  and  sink,  and  literally 
covered  the  floors.  Six  fruit  jars  containing  the  Nickels  sirup  and 
sponges  were  placed  in  different  rooms  in  the  house,  and  6  paraffined 
paper  bags  containing  the  same  sirup  and  a  sponge  were  placed 
around  the  house  outdoors  on  trees,  fence,  and  back  porch.  The 
sirup  was  about  a  month  old.  The  experiment  was  begun  at  1  p.  m. 
At  5  p.  m.  hardly  an  ant  was  to  be  seen  in  the  house,  although  a  few 
Avere  to  be  found  at  each  jar  and  many  were  visiting  the  bags.  Two 
days  later  .not  an  ant  could  be  found  in  the  house  and  only  three  erf 
the  bags  were  attended  by  ants.  As  it  seemed  impossible  that  the 
colonies  could  have  been  exterminated  so  quickly,  the  adjacent  vacant 
lot  was  inspected.  This  lot  was  overgrown  with  weeds,  and  in  a 
corner  near  the  house  there  was  a  pile  of  old  lumber.  Ants  were 
found  in  abundance  nesting  in  the  lumber,  and  many  were  present 
wherever  they  could  find  dry  quarters  in  the  lot.  It  was  quite  evident 
that  the  ants  had  been  repelled  by  the  poison. 

A  series  of  experiments  to  obtain  definite  data  on  the  repellent 
properties  of  the  sirup  were  conducted  in  the  Horticultural  Hall, 


16 


BULLETIN    377,    U.    S.    DEPARTMENT   OF    AGRICULTURE. 


Audubon  Park,  New  Orleans,  with  the  Nickels  sirup  in  the  strength 
as  recommended  originally,  and  also  double,  half,  and  quarter 
strengths.  One  gill  of  sirup  was  used  to  a  jar,  each  jar  being 
placed  on  its  side  to  give  free  access  to  the  ants,  to  prevent  the 
entrance  of  water,  and  to  prevent  mold.  The  "  Hall "  furnished 
ideal  conditions  for  the  experiment,  the  temperature  throughout  the 
year  being  kept  high  and  uniform.  The  abundance  of  various 
species  of  scale  insects  and  aphids  attracted  the  ants  in  great  num- 
bers at  all  seasons,  but  especially  in  cold  and  wet  weather.  Three 
jars  of  each  strength  were  used  and  observations  were  made  fre- 
quently for  a  period  of  32  days.  At  the  time  of  this  experiment 
the  ants  were  very  numerous,  due  to  the  extremely  wet  summer  of 
1912.  The  rate  of  attendance  and  relative  repellent  value  of  the 
four  strengths  of  the  poison  are  shown  graphically  in  the  first  part  of 
Table  I. 

TABLE!. — Experiments  u~it  ft  sodium  arsenite  (NaAs00)  added  (in  Jour  strengths*) 
to  sugar  sirup  solution,  1912. 

[Symbols:  A=  Heavily  visited  by  ants.    B=Only  attended  by  a  few  ants.    C=Not  attended  by  ants  ] 
FIRST  TEST,  IN  HORTICULTURAL  HALL. 


Date. 

Double  strength. 

Nickels  solution. 

Half  strength. 

Quarter  strength 

JuneS  

June  10  
June  12  

A 
B 
A 
B 
B 
B 
A 
B 
B 
A 
C 
B 
C 
C 

c 
c 

B 
B 
B 
C 
C 
A 
B 
B 
A 

\ 

B 

I 

C 

A 
B 
A 
B 

B 
B 
A 
B 

A 
A 
A 

A 

A 
A 

A 

A 
A 

A 
A 
A 

A 
A 
B 
A 
A 
A 
A 
A 
C 
A 
A 
C 
A 
C 
A 

A 
B 
A 
A 
C 
A 
A 
A 
C 
C 
C 
C 
C 
C 
A 

A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
C 

A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
B 
A 
A 
A 

June  13  
JuneH  

June  17  
June  19  

June  21 

A 
B 
A 

! 
1 

c 
c 
c 

A 
A 
A 
C 
B 
C 
C 
C 

c 
c 
c 

A 
A 
A 
A 
C 
A 
A 
A 
C 
C 

c 

A 
A 
A 
A 
C 
B 
C 
C 
A 
A 
A 

A 
A 
A 
A 
A 
A 
A 
A 
A 
A 
A 

B 
A 
A 
A 
A 
C 
C 
A 
B 
A 
B 

June  22  

June  26  
June  28 

Julyl  

July  2    .             

July  5  
JulyS 

July  10  

DUPLICATE  EXPERIMENT,  USING   PAPER-BAG  SIRUP  CONTAINERS  TACKED  ON  FIG 
TREES  (OUTDOORS). 


July26  

July  28 

A 
B 

A 
B 

C 

c 

A 
B 

A 
B 

B 
B 

A 
A 

A 
A 

A 
B 

A 
A 

C 
A 

A 
A 

July  29 

A 

A 

B 

B 

A 

A 

A 

A 

A 

A 

A 

July  30    

A 

B 

C 

C 

A 

A 

A 

A 

B 

A 

A 

A 

JulySl  

C 

B 

C 

B 

A 

B 

A 

A 

A 

A 

A 

A 

c 

c 

c 

c 

B 

A 

A 

A 

A 

\ 

A 

A 

Augusts  

B 

C 

c 

A 

A 

A 

A 

A 

A 

A 

A 

Augusts  

A 

A 

c 

A 

B 

B 

A 

B 

A 

A 

A 

August  14 

B 

B 

c 

A 

A 

A 

A 

A 

A 

A 

August  16  

B 

C 

A 

A 

A 

B 

A 

A 

A 

A 

A 

August  19  
August  21  

\ugust  23 

B 

C 
B 

B 

C 

c 

C 
B 

c 

A 
B 
A 

B 
A 
A 

B 
C 
B 

A 
A 
A 

A 
A 
B 

A 
B 
A 

A 
A 
B 

A 

A 
A 

August  26  

A 

c 

B 

A 

A 

A 

A 

B 

A 

A 

A 

August  29  
August  31  

A 

A 

B 
A 

C 

C 

A 
A 

B 
B 

C 
B 

A 
A 

A 
B 

B 

A 

A 
A 

A 
A 

A 
A 

Double  strength 

Nickels  solution-- 
Half strength 

Quarter  strength. 


.10  pounds  granulated  sugar  +  T>  pounds  II_>O  +  1  ounce  NaAsO2. 
.10  pounds  granulated  sugar  +  5  pounds  H2O  +  J  ounce  NaAsO2. 
-10  pounds  granulated  sugar  +  5  pounds  II2O  +  ',  ounce  NaAsO2. 
_10  pounds  granulated  sugar  +  5  pounds  H2O  +  i  ounce  NaAsOg. 


THE  ARGENTINE   ANT:   DISTRIBUTION   AND  CONTROL.  17 

The  experiment  was  duplicated,  except  that  the  sirups  were  placed 
in  waxed  paper  bags  tacked  on  fig  trees.  These  bags  each  held  a 
gill  of  sirup,  and  sponges  were  placed  in  the  sirup  to  allow  easy 
access  of  the  ants.  At  the  time  of  conducting  the  experiment  the 
figs  were  ripening  and  the  ants  were  visiting  the  trees  in  immense 
numbers.  It  will  be  seen  from  the  second  part  of  Table  I  that  the 
results  were  substantially  the  same  as  in  the  indoor  experiments. 
The  two  experiments  may  be  summarized  as  follows : 

The  most  concentrated  sirup  (2  ounces  sodium  arsenite)  at- 
tracted great  numbers  of  ants  in  only  32  counts,  few  ants  in  34 
counts,  and  no  ants  whatever  in  39  counts. 

The  standard  Nickels  sirup  (1  ounce  sodium  arsenite)  attracted 
great  numbers  in  62  counts,  few  ants  in  25  counts,  and  no  ants  in 
18  counts. 

The  half-strength  solution  (|  ounce  sodium  arsenite)  attracted 
great  numbers  in  88  counts,  few  ants  in  12  counts,  and  no  ants  in  5 
counts. 

The  quarter-strength  solution  (£  ounce  sodium  arsenite)  attracted 
great  numbers  in  92  counts,  few  ants  in  4  counts,  and  no  ants  in  9 
counts. 

The  experiments  prove,  therefore,  that  the  excessive  quantities  of 
the  arsenic  in  a  sirup  will  cause  it  to  become  repellent.  The  observa- 
tions also  indicate  that  the  sirup  decomposed  more  rapidly  as  the 
amount  of  the  sodium  arsenite  increased. 

Dr.  W.  E.  Cross,  research  chemist  of  the  sugar  experiment  station 
at  Audubon  Park,  was  consulted  with  regard  to  the  various  defects 
in  the  Nickels  sirup.  His  explanations  and  suggestions,  which  were 
of  great  importance  in  the  further  conduct  of  the  investigations,  are 
given  below. 

When  granulated  sugar  (or  sucrose)  is  heated,  it  is  partially 
changed  to  invert  sugar  (or  glucose),  and  if  to  this  is  added  sodium 
arsenite,  which  has  an  alkaline  reaction,  chemical  decomposition 
takes  place.  When  heated  this  reaction  is  hastened  and  the  com- 
pound becomes  darker  and  darker.  On  account  of  the  instability  of 
the  sirup,  it  will  further  decompose  on  standing  and  the  final  prod- 
uct will  be  a  substance  with  an  unpleasant  odor  and  taste.  The 
addition  of  a  small  quantity  of  tartaric  acid  to  the  sugar  sirup 
before  adding  the  sodium  arsenite  will  produce  a  greater  inversion 
of  the  sucrose,  thus  lessening  the  danger,  of  crystallization,  and  will 
neutralize  the  alkalinity  of  the  sodium  arsenite,  preventing  decom- 
position. If  a  slight  acid  reaction  is  obtained  the  sirup  will  keep 
indefinitely.  The  inversion  of  the  sucrose  reduces  the  sweetness  of 
the  sirup,  and  to  balance  this  7  per  cent  of  pure  hone}7  is  added. 


18  BULLETIN   377,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

The  preparation  finally  proposed  by  Dr.  Cross  is  made  as  follows : 

Prepare  a  sirup: 

Granulated  sugar pounds 15 

Water pints—     7 

Tartaric  acid  (crystallized)1 ounce—       i 

Boil  for  30  minutes.    Allow  to  cool. 

Dissolve  sodium  arsenite  (C.  P.) ounce__       I 

In  hot  water pint—     1 

Cool.*    Add  poison  solution  to  sirup  and  stir  well.    Add  to  the 
poisoned  sirup: 

Honey pounds 1J 

Mix  thoroughly. 

On  April  23, 1914,  Dr.  Cross  and  the  writer  prepared  two  sirups  of 
the  above  formula  (exclusive  of  the  honey,  which  only  makes  the 
sirup  more  palatable) ,  except  that  one  lacked  the  tartaric  acid.  After 
cooling,  they  were  tested  in  a  refractometer,  with  the  following 
results : 

Sirup  with  tartaric  acid,  specific  gravity  1.339,  Brix  (sugar  content)  68.8. 
Sirup  without  tartartic  acid  (Nickels  sirup),  specific  gravity  1.343,  Brix  68.05. 

The  Nickels  sirup  had  lost  0.75  per  cent  of  its  sugar  content  and 
was  of  a  very  dark  brown  color.  The  new  sirup  wras  bright  yellow 
(amber  color),  clear,  and  transparent.  Equal  samples  of  each  were 
placed  in  quart  exhibit  jars  writh  ground-glass  stoppers,  labeled,  and 
set  aside.  A  second  reading  was  made  on  June  20,  1914,  as  follows: 

Sirup  with  tartaric  acid,  specific  gravity  1.340,  Brix  68.40. 
Nickels  sirup,  specific  gravity  1.3321,  Brix  67.01. 

The  new  sirup  had  lost  0.4  per  cent  of  its  total  solids  and  had  not 
noticeably  changed  in  color  or  sweetness.  The  Nickels  sirup  had  lost 
1.04  per  cent  of  its  total  solids,  wras  nearly  black,  partly  crystallized, 
and  had  lost  much  of  its  sweetness.  In  the  beginning  of  August  the 
stoppers  were  removed  and  cheesecloth  tied  over  the  mouths  of  both 
jars,  to  find  how  evaporation  would  affect  these  sirups.  The  jars 
were  placed  on  a  shelf  in  the  laboratory.  In  the  beginning  of 
January,  five  months  after  the  jars  were  first  left  open,  they  were 
examined.  Figure  2  shows  the  conditions.  The  difference  in  the 
quantity  of  the  sirups,  in  color,  and  in  the  crystallization  that  had 
taken  place  within  the  jar  containing  the  Nickels  sirup  may  readily 
be  noted.  A  reading  was  taken  of  these  sirups,  as  follows : 

Sirup  with  tartaric  acid,  specific  gravity  1.385,  Brix  75.48. 
Nickels  sirup,  1.367,  Brix  72.68. ' 

1  In  the  first  experiments  one-half  ounce  of  tartaric  acid  was  used,  hut  this  is  found 
unnecessary. 

2  In  earlier  experiments  the  sirup  was  boiled  30  minutes  after  addition  of  the  poison, 
but  boiling  will  raise  the  "  Brix  "  (total  solids),  which  is  to  the  disadvantage  of  the  sirup 
as  an  ant  bait. 


THE    ARGENTINE    ANT:    DISTRIBUTION    AND   CONTROL. 


19 


The  Nickels  sirup1  was  then  drained  from  its  jar  and  was  found 
to  weigh  160  grams.  The  jar  and  crystals  were  then  weighed,  the 
crystals  dissolved  out  of  the  jar,  and  the  weight  of  the  jar  subtracted 
from  the  total  weight  of  the  jar  and  crystals.  It  was  found  that  333 
grams  of  sugar  crystals  were  present. 

Grams. 

Weight  of  sirup  when  first  made 660.  23 

AVeight  of  sirup  remaining  +  sugar  crystals 493.  00 


Water  passed  off  by  evaporation  ____________________  167.  23 

The  660.23  grams  of  sirup  contained  1.333  grams  of  sodium  arsenite  with  a 

poison  content  of  0.202  per  cent. 

The  160  grams  of  sirup  remaining  contained  1.333  grams  of  sodium  arsenite. 

The  poison  content  was  now  0.836  per  cent. 

The  sirup  with  tartaric  acid  had  a  small  precipitation.  As  the 
Brix  had  been  raised  7.4  per  cent  through  evaporation,  the  poison 
content  was  very  slightly 
raised.  This  sirup  now 
weighed  643.35  grams,  the 
color  and  sweetness  being  still 
quite  stable. 

Immediately  after  prepar- 
ing these  two  sirups,  April 
23,  1914,  2  fruit  jars  of  each, 
containing  1£  gills  of  sirup 
apiece  (Without  honey),  were 
set  out  along  heavy  ant  trails 
in  the  Horticultural  Hall. 
xVbsolutely  clean  and  odorless 
sponges  were  used. 

For  the  first  4  days  the  ants 
showed  a  preference  for  the 
old  type  of  sirup  (without 
the  tartaric  acid)  but  for  the 

,  .-I  i  i 

next  21  Clays  they  ShOAVed  no 


FIG.  2.  —  Comparison  of  the  improved  simp  (right) 
with  the  Nickels  sirup  (left),  showing  the  amount 
of  sirup  loft  in  each  and  the  amount  of  sugar  in 
the  Nickels  sirup.  (Original.) 


preference.      Then  One   jar   of 
!,          ,,      .  ,          i 

the  old  sirup  was  abandoned. 
This  proATed  to  be  partially  decomposed.  On  moAdng  to  another  spot 
it  was  attended  for  10  days  more,  then  abandoned  completely.  Thus 
for  a  total  of  35  days  this  jar  attracted  the  ants.  Seven  days  later 
the  other  jar  of  this  sirup  was  abandoned  and  no  matter  where  placed 
neither  jar  had  any  attraction  for  the  ants. 

1  Figure  3  shows  the  small  quantity  of  sirup  that  still  remained,  as  well  as  the  large 
bulk  of  sugar  crystals  which  had  formed  in  the  jar.  The  jar  containing  the  acidified 
sirup  is  placed  at  the  side  for  comparison. 


20 


BULLETIN    377,    U.    S.    DEPARTMENT   OF    AGRICULTURE. 


The  jars  with  the  new  type  of  sirup  were  visited  constantly  for 
62  days,  or  to  the  conclusion  of  the  experiment.  The  small  amount 
of  sirup  left  was  still  clean  and  as  sweet  as  at  first. 

Tests  of  the  poisonous  qualities  of  both  liquids  were  made  with 
colonies  in  Janet  cages,  under  control  as  to  food.  There  was  prac- 
tically no  difference  in  toxicity.  Workers  in 
both  cages  began  to  die  in  4  days,  the  queens 
stopped  ovipositing  in  14  days,  and  winged 
males  died  very  quickly,  the  queens  in  17  days, 
and  the  whole  colony  in  each  case  was  extermi- 
nated on  the  thirty-second  day. 


PRACTICAL   TESTS    OF   THE   IMPROVED    SIRUP. 

The  new  sirup,  made  exactly  as  in  the  for- 
mula given  above,  is  very  palatable  to  the  ants 
at  any  season  of  the  year.  It  was  found  that 
containers  charged  with  it  placed  at  selected 
points  outside  a  residence  would  attract  the 
ants  and  they  would  cease  to  invade  the  house. 
A  private  residence  in  a  large  plot  of  ground 
on  a  street  corner  with  a  row  of  large  oak  trees 
along  each  street  was  heavily  infested  with 
ants,  which  were  to  be  found  in  the  sink,  the 
refrigerator,  all  over  the  floors,  etc.  On  June 
18,  6  cans  each  containing  this  sirup  and  a 
spovg*  were  hung  on  the  brick  pillars  which 
im-  supported  the  house.  The  following  morning 
there  was  scarcel  an  ant  to  be  seen  in  the 


FIG.  3. — Comparison  of  the 
improved     sirup     (left) 


evaporation.      The 
proved     sirup     is     still 
clear  and   sweet,   while 

the  Nickels  sirup  is  house  and  the  ants  were  attending  the  sirup 
in  large  numbers.  The  same  conditions  existed 
throughout  the  length  of  the  experiment,  which 

was  terminated  on  August  10.     Many  such  small  experiments  have 

been  conducted,  the  results  being  equally  successful. 


dark  and  full  of  crys- 
tals and  decayed  mat- 
ter. (Original.) 


APPLICATION  OF  THE  SIRUP. 


The  paraffin-covered  paper  bag1  shown  in  figure  4  is  undoubtedly  the 
cheapest  container.  It  can  be  made  in  large  quantities  at  a  cost  of  about 
$5  per  thousand.  Small  1-pound  bags  used  in  grocery  stores  are  ob- 
tained, and  two  or  three  holes  about  one-fourth  inch  in  diameter  are  cut 
through  each  folded  bag  with  a  leather-punch  or  similar  instrument. 
This  provides  each  bag  with  two  holes  on  each  side  for  the  entrance 
of  the  ants.  Being  opened,  the  bags  are  dipped  in  a  pan  of  molten 

1  The  writer  is  indebted  to  Mr.  R.  W.  Moreland,  Bureau  of  Entomology,  for  his  sugges- 
tions in  the  preparation  of  this  waterproof  container. 


THE  ARGENTINE   ANT  :   DISTRIBUTION   AND  CONTROL. 


21 


paraffin  and  set  aside  to  dry.  The  paraffin,  forming  a  waterproof  sur- 
face, materially  lengthens  the  life  of  the  bag,  which  is  protected  from 
the  entrance  of  water  through  the  holes 
by  part  of  another  (2-pound)  paraffined 
bag  which  covers  the  first  one  like  a  can- 
opy. In  use,  each  bag  is  provided  with  a 
small  quantity  of  poisoned  sirup  and  a 
piece  of  sponge,  the  protecting  outer 
piece  of  bag  is  drawn  up  over  it,  and 
the  ends  of  both  are  folded  over  at  the 
top  and  tacked  to  a  tree.  On  account 
of  the  bag  coming  together  at  the  top 
it  is  very  narrow  at  the  point  where 
the  entrance  holes  are  made;  conse- 
quently very  small  pieces  of  sponge  are 
required.  The  bags  have  been  known 
to  last  for  long  periods,  but  the  larger 
percentage  of  them  last  only  about  2  or 

3  months.      They  Can  not  be  recharged.    FIG.  4. Paraffined  paper  bags   ar- 

Thp    fin     pqn        ranged    as    a    container    for    ant 
poison  sirup.     The  apron  has  been 

shown  in  figure        cut    away    to    show    the    ant    en- 
r     •        ,1  trance  holes.    Such  bags  are  nailed 

O     IS     the     most        totpees.     ( original.) 

satisfactory 

container.  ,Any  sized  can  may  be  used,  but 
the  handiest  size  is  the  one-half  pound  bak- 
ing-powder can.  The  can  must  have  a  fric- 
tion cover,  and  of  course  it  must  hold  water. 
If  the  can  is  indented  deeply  on  the  two  op- 
posite sides  (as  illustrated  in  the  drawing, 
fig.  5)  and  the  cover  replaced,  it  will  be  ob- 
servable that  there  is  ample  space  between 
the  top  of  the  can  and  the  cover  for  the  en- 
trance of  the  ants,  and  the  can,  if  kept  in  an 
upright  position,  will  be  weatherproof. 
About  a  gill  of  the  sirup  will  be  sufficient  for 
several  months,  but  in  heavy  infestations  it  is 
better  to  put  2  gills  in  each  can.  Tt  is  very 
advisable  to  place  a  fairly  large  piece  of 
sponge  in  the  can.  The  sponge  will  float  on 
experiments,  the  sirup  and  allow  the  ants  to  feed  in  large 
numbers.  A  piece  of  wire  about  6  inches 
long  may  be  bent  for  a  handle,  a  hook  inward  at  each  end  being  made. 
The  hooks  may  be  attached  under  the  lid  of  the  can  where  it  projects 
over  the  part  that  has  been  indented.  This  forms  a  handle  by  which 


in     outdoor 
(Original.) 


22  BULLETIN    377,    U.    S.    DEPARTMENT   OF    AGRICULTURE. 

the  cans  may  be  hung  on  trees,  fences,  walls  of  houses,  etc.  The  ants 
prefer  to  climb  for  their  food,  and  it  is  well  to  hang  the  cans  near  ant 
trails  going  up  trees,  walls,  etc.  It  is  advisable  to  hang  the  cans  in 
the  shade  to  prevent  the  evaporation  of  the  sirup,  for  though  it  has 
been  proved  that  evaporation  does  not  affect  this  sirup  to  a  marked 
extent,  it  is  well  to  avoid  raising  the  solid  contents  of  the  liquid. 
Eight  to  ten  of  these  cans  should  be  sufficient  to  place  around  an 
ordinary  city  house  and  lot.  If  the  grounds  are  large  and  if  many 
trees  are  present,  more  cans  should  be  placed  out. 

From  the  results  so  far  obtained,  the  careful  preparation  of  the 
poisoned  sirup  can  not  be  too  highly  emphasized.  Very  accurate 
balances  are  necessary  for  the  weighing  out  of  the  poison  and  the 
tartaric  acid.  This  is  especially  true  when  small  quantities  of  the 
sirup  are  prepared. 

PLANS  FOR  MUNICIPAL  CONTROL  WORK. 

In  effecting  control  in  towns  and  cities  it  is  first  necessary  to  ascer- 
tain the  extent  of  the  infestation.  This  should  be  mapped  out  so  that 
workmen  in  distributing  the  cans  will  be  able  to  refer  to  the  map  to 
insure  the  covering  of  the  entire  territory.  Cans  may  be  obtained  at 
wholesale  at  about  $16  per  thousand.  About  10  pounds  of  "  grass  " 
sponges  will  be  required  per  1,000  cans.  These  will  cost  about  75 
cents  per  pound.  The  sponges  should  be  thoroughly  washed  and  dried 
before  use.  When  wet  they  may  easily  be  torn  into  pieces  about 
2  by  2  inches.  Using  1  gill  of  sirup  per  can,  200  pounds  of  granu- 
lated sugar  will  be  required  per  1,000  cans.  The  cost  of  the  sodium 
arsenite  is  about  80  cents  per  pound,  and  1  pound  will  be  sufficient 
for  1,500  cans.  Tartaric  acid  (crystallised)  costs  about  TO  cents  a 
pound,  which  will  be  enough  for  4,500  caws.  From  60  to  100  cans 
will  be  required  per  block,  depending  on  the  size  of  the  block.  The 
late  fall,  \vinter,  and  spring  are  the  most  desirable  times  in  which  to 
do  this  work,  as  in  these  seasons  the  natural  food  is  least  plentiful 
and  the  ants  most  hungry.  Two  men  should  be  able  to  prepare  the 
sirup,  wash  and  tear  up  the  sponges,  and  charge  about  2,000  cans  per 
day  and  distribute  about  1,000  cans  per  day. 

TRAPPING  ANTS. 

By  taking  advantage  of  their  winter  colonizing  habit  the  ants  may 
be  attracted  in  large  numbers  to  specially  prepared  trap  boxes,  which 
may  be  fumigated  when  large  numbers  have  gathered  in  these  boxes 
for  winter  nesting.  Newell  and  Barber,  who  originated  this  method 
of  control,  describe  in  Bureau  of  Entomology  Bulletin  122  some  very 
interesting  and  successful  trap-box  experiments.  The  boxes  were 
filled  with  decaying  vegetation,  the  heat  generated  making  them  very 
attractive  as  hibernating  quarters.  Carbon  bisulphid  was  found  to 


THE   ARGENTINE   AXT  :    DISTRIBUTION   AND   CONTROL.  23 

be  the  best  and  most  economical  fumigant  for  use  in  the  trap  boxes. 
It  is  hardly  necessary  to  state  that  this  method  of  control  is  not  ap- 
plicable to  city  conditions,  where  dry  nesting  quarters  are  very 
plentiful  and  the  ants  do  not  colonize  to  any  great  extent. 

SUMMARY  OF  CONTROL  MEASURES. 

ANT    BAKBIERS. 

In  grossly  infested  houses  much  relief  may  be  secured  by  isola-ting 
tables,  refrigerators,  safes,  beds,  etc.,  with  bichlorid-of-mercury  tape, 
or  by  placing  the  legs  of  articles  of  furniture  in  saucers  filled  with 
moth  balls  or  coal  oil.  Trees,  beehive  stands,  and  other  outdoor  ob- 
jects may  be  isolated  with  the  sticky  substance  used  on  fly  paper  but 
made  thinner  than  usual.  If  5  per  cent  of  carbolized  oil  be  added, 
the  durability  of  the  bands  will  be  considerably  increased. 

REPELLENT   ANT   POISONS. 

Kepellents  are  much  used  to  keep  the  ants  from  buildings.  Strong 
untimony  or  arsenical  sirups,  a  number  of  which  are  sold  by  drug- 
gists in  infested  territory,  are  used  for  this  purpose.  They  give 
quick  relief  for  short  periods,  but  they  are  not  a  factor  in  the  reduc- 
tion of  the  infestation. 

ATTRACTIVE   ANT   POISONS. 

The  only  effective  poisons  yet  known  for  permanent  control  are 
poisoned  sirups.  The  improved  arsenical  sirup  recommended  on 
page  18  will  not  spoil  and  is  superior  to  any  other  formula  yet  tested 
on  account  of  its  stability  at  high  temperatures,  freedom  from  crys- 
tallization, and  continued  attractiveness. 

TRAPPING  ANTS. 

Trapping  ants  may  be  accomplished  in  rural  locations  by  provid- 
ing boxes  of  decaying  vegetation  in  the  winter.  The  colonies  will 
move  into  these  boxes  and  the  ants  may  then  be  killed  with  carbon 
bisulphid. 


WASHINGTON  :    GOVERNMENT  PRINTING  OFFICE:   1916 


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